Study on Intermetallic Phase Formation in Directionally Solidified Al-Si-Fe Alloys with Trace Elements

摘要

Present study investigated the observation of intermetallic phase formation, in Al-7Si-0.9Fe and Al-7Si-0.9Fe-trace (0.3 percent Mn and 0.3 percent Cr) alloys, as a function of growth rate in Bridgman solidification. The Bridgman QDS technique allows close control of the solidification conditions and resulting sample can provide detail information on intermetallic phase formation in these alloys. These alloys were solidified unidirectionally with different growth rates (1-30 mm/min). Based on these results, solidification of these alloys consists of the growth of primary aluminium and multiple second phase reactions. In the Al-Si-Fe alloys, two type of iron-rich phase form during the directional solidification. When small amounts of Mn and Cr are present, another phase with different morphology appears. The morphology of all types of intermetallic was dependent on cooling rate.